There are many applications in which sheets must be fed singly from a stack to a downstream position. One important application is in reproduction apparatus such as electrostatic reproduction apparatus in which blank sheets are held in a stack and then fed singly through the apparatus to a reproduction station where an image is transferred onto the sheet, the sheet then being fed on to an outlet. A further example is a duplex tray within reproduction apparatus for use when images are to be reproduced on both sides of the sheet. In this situation, a blank sheet is fed to the reproduction station so that an image can be reproduced on one side of the sheet, the sheet then being fed to a temporary storage location defined by a duplex tray where the sheet can be flipped in its orientation and then drawn out and fed back through the reproduction station so that a further image can be reproduced on its other side.
In all applications where sheets are to be fed singly from a stack, it is important to prevent more than one sheet being fed simultaneously. Conventionally, this is achieved by using counter running rolls or nips and the like.